The present invention relates to an indexable cutting insert for an end mill for the machining of contours in a workpiece and to a milling tool, which correspond to EP-A1-842 723.
An end mill is used under complicated and severe conditions with intensely fluctuating cutting forces under heavy demands regarding the machining precision. If indexable cutting inserts are used for an end mill, it is important to place such indexable cutting inserts precisely in relation to the tool body and to clamp the cutting insert rigidly on the tool body.
A conventional indexable cutting insert for an end mill, see, for instance, U.S. Pat. No. 6,149,355 and U.S. Pat. No. 5,951,213, has two cutting edges, each comprising a curved edge and a substantially straight edge connecting to one end thereof. In its entirety, the cutting insert has an oval shape as seen in top view. Thus, if the cutting insert is a positive cutting insert, i.e., a cutting insert having a leaning side, it is very difficult to precisely position the cutting insert on a tool body and clamp the same rigidly. Other documents of interest are EP 0842723A1, EP 1252955 A1 and U.S. Pat. No. 6,149,355.
It is desirable to provide a milling tool for precise positioning of the cutting insert.
It is desirable to provide a milling tool wherein the cutting insert may be clamped rigidly.
It is desirable to provide a cutting insert that enables rigidly clamping in the tool body.
According to an aspect of the present invention, a milling tool comprises a shaft and a front chip-removing end. The end has at least one cutting insert pocket comprising a boring. The tool comprises an indexable cutting insert receivable in the pocket, and a clamp arranged to hold the cutting insert in the cutting insert pocket. The cutting insert is asymmetrical in respect of a line through a hole in the cutting insert, the cutting insert comprising two cutting edge portions, each cutting edge portion comprising a substantially straight cutting edge and a curved cutting edge along respective intersecting lines between a clearance surface and a chip surface, the curved cutting edges having different lengths. The cutting insert pocket and the cutting insert comprise cooperating projections and recesses, wherein the projections are arranged on both sides of and at different distances from the boring and the recesses are arranged on both sides of and at different distances from the hole of the cutting insert.
According to another aspect of the invention, an indexable cutting insert for a milling tool is provided. The cutting insert is asymmetrical in respect of a line through a hole in the cutting insert. The cutting insert comprises two cutting edge portions, each cutting edge portion comprising a substantially straight cutting edge and a curved cutting edge along respective intersecting lines between a clearance surface and a chip surface, the curved cutting edges having different lengths, the cutting insert comprising recesses in a bottom side of the cutting insert. The recesses are arranged on both sides of and at different distances from the hole of the cutting insert.